Auto merge of #4031 - torkleyy:exclude, r=alexcrichton
authorbors <bors@rust-lang.org>
Sat, 27 May 2017 23:36:45 +0000 (23:36 +0000)
committerbors <bors@rust-lang.org>
Sat, 27 May 2017 23:36:45 +0000 (23:36 +0000)
Add --exclude flag

Allows to exclude packages in conjunction
with --all.

Addresses #2878


Trivial merge